| // Copyright 2011 The Closure Library Authors. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS-IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| /** |
| * @fileoverview Provides a convenient API for data persistence using a selected |
| * data storage mechanism. |
| * |
| */ |
| |
| goog.provide('goog.storage.Storage'); |
| |
| goog.require('goog.json'); |
| goog.require('goog.storage.ErrorCode'); |
| |
| |
| |
| /** |
| * The base implementation for all storage APIs. |
| * |
| * @param {!goog.storage.mechanism.Mechanism} mechanism The underlying |
| * storage mechanism. |
| * @constructor |
| */ |
| goog.storage.Storage = function(mechanism) { |
| /** |
| * The mechanism used to persist key-value pairs. |
| * |
| * @protected {goog.storage.mechanism.Mechanism} |
| */ |
| this.mechanism = mechanism; |
| }; |
| |
| |
| /** |
| * Sets an item in the data storage. |
| * |
| * @param {string} key The key to set. |
| * @param {*} value The value to serialize to a string and save. |
| */ |
| goog.storage.Storage.prototype.set = function(key, value) { |
| if (!goog.isDef(value)) { |
| this.mechanism.remove(key); |
| return; |
| } |
| this.mechanism.set(key, goog.json.serialize(value)); |
| }; |
| |
| |
| /** |
| * Gets an item from the data storage. |
| * |
| * @param {string} key The key to get. |
| * @return {*} Deserialized value or undefined if not found. |
| */ |
| goog.storage.Storage.prototype.get = function(key) { |
| var json; |
| try { |
| json = this.mechanism.get(key); |
| } catch (e) { |
| // If, for any reason, the value returned by a mechanism's get method is not |
| // a string, an exception is thrown. In this case, we must fail gracefully |
| // instead of propagating the exception to clients. See b/8095488 for |
| // details. |
| return undefined; |
| } |
| if (goog.isNull(json)) { |
| return undefined; |
| } |
| /** @preserveTry */ |
| try { |
| return goog.json.parse(json); |
| } catch (e) { |
| throw goog.storage.ErrorCode.INVALID_VALUE; |
| } |
| }; |
| |
| |
| /** |
| * Removes an item from the data storage. |
| * |
| * @param {string} key The key to remove. |
| */ |
| goog.storage.Storage.prototype.remove = function(key) { |
| this.mechanism.remove(key); |
| }; |